Add tests to make sure rules have tests

[mrmans0n]

This is to make sure external contributors don't forget to add the detekt/ktlint version of the rules (I've had some instances of this, people typically forget to include the ktlint version), and that all rules in both detekt/ktlint have unit tests.

This would make working in this repo more straightforward, as tools would yell at you if you forget something. It's a lot, and it's getting hard to track, I know 😆